Damn, I got this annoying "The Web at http://localhost/myProject" already contains a project." from VSS again. I found this useful help on how to fix this with a little .sln hack (original forum: http://www.relisoft.com/forums/index.php?showtopic=52).
I'm quoting here, but this worked fine for me:
1. You need to manually edit the sln file.
- Remove the information about the problematic project. Find and delete these 4 lines :
SccProjectUniqueName1 = http://localhost/SolutionName/SolutionName.csprojSccLocalPath1 = .
CanCheckoutShared = true
SccProjectEnlistmentChoice1 = 2
- Also decrement the SccNumberOfProjects value by 1.
2. Open the sln in the VS. It will put out some dialogs with complains, but don't care about them now.
3. Go to File.Source Control.Change Source Control dialog. Select the problematic project and Bind it (using the Bind button). VS will make all necessary changes to the sln file.
Allthough my context was a little different, it worked fine all the same. My solution had three web projects (one website, and two webservices). All three of them gave me the same problem, but editing exactly as stated above solved the problem for me.